The present invention relates to a carton unloading and erecting apparatus. More particularly this invention concerns a system for taking a flat box blank out of a supply, erecting it, and setting it on a conveyor leading to a filling or further handling device.
Packing cartons are typically produced off site and delivered to the location where they are used in flattened condition in stacks. Before being used the cartons must be separated from the stack and erected, that is transformed from the flattened basically planar shape to an erect three-dimensional and normally parallepipedal shape.
Typically the stack of flattened cartons is loaded into a supply magazine having an outlet end that is formed with narrow retaining lips. The stack is pushed against the lips which are big enough to prevent the stack from moving outward out of the magazine. A suction gripper is normally engaged against the frontmost carton of the stack and moves outward to pull it past the retaining lips, then pivots around to set the carton on an erector or on a conveyor taking the erect box to a further treatment station, for instant a filling device.
In U.S. Pat. No. 5,456,381 a supply magazine holds a stack of flattened cartons in which the cartons extend in respective parallel planes and where the stack has an end formed by a frontmost carton . A device for picking the cartons off the stack starting with the frontmost carton includes a grab displaceable along a path passing through a pickup point and operable when at the point to engage and grip the frontmost carton, and a system for displacing the path and thereby moving the location along a generally straight line for setting the picker for cartons of different height. The carton-supply system has a stationary support adjacent the grab path, a supply magazine having a plurality of guide elements extending parallel to a predetermined feed direction and holding the stack of cartons with their planes substantially perpendicular to the feed direction and with the plane of the frontmost carton defining a predetermined acute pickoff angle with the line of the grab, and an adjustment system supporting the magazine guide elements on the support for straight-line movement in an adjustment direction forming with the feed direction an angle equal to generally half of the pickoff angle and for arresting the magazine in any of a multiplicity of positions offset from each other in the adjustment direction.
This arrangement is extremely effective with respect to adapting to cartons of different sizes. The adjustment requires that the supply magazine be made vertically adjustable which complicates the equipment.
In another known system described in U.S. Pat. No. 4,871,348 the carton delivery apparatus removes cartons, one by one, which are already scored and stored in a stack in a magazine, folded down flat against each other. A suction mechanism removes cartons one by one from the magazine by holding and delivering it to a conveyor. The suction mechanism is mounted on a member which is rotatable about a horizontal shaft disposed between the magazine and the conveyor. The suction mechanism is also rockable about a support shaft which is mounted on the member so that, as the member rotates, the suction mechanism removes a carton and delivers it to the conveyor while holding it on its lower side. Once again, this system requires that the supply magazine""s position be adjusted when the carton size changes. Such construction is particularly troublesome in that the equipment is very complex and often fits together with little extra room.
It is therefore an object of the present invention to provide an improved unloading and erecting apparatus for cartons.
Another object is the provision of such an improved unloading and erecting apparatus for cartons which overcomes the above-given disadvantages, that is which allows carton format to be changed without having to make any position changes to the supply chute or magazine.
These objects are attained in a system used in combination with a magazine holding a stack of flattened cartons with the cartons extending in respective parallel and generally vertical planes and the stack having an end formed by a frontmost carton and a conveyor below the magazine and adapted to carry off erected cartons in a forward transport direction. The unloading and erecting apparatus according to the invention has a frame fixed to the magazine adjacent the conveyor, an outer horizontal guide on the frame, an outer horizontal slide horizontally displaceable on the outer horizontal guide in the forward direction and in an opposite backward direction and carrying two differently shaped and nonstraight outer vertical guides, and a drive motor connected to the outer horizontal slide for horizontally displacing same on the outer horizontal guide. A vertical guide on the frame carries a vertical slide and another drive motor connected to the vertical slide vertically displaces same on the vertical frame guide. A shaft pivotal about a generally horizontal axis transverse to the forward direction on the vertical slide is fixed horizontally relative to the outer horizontal slide. A gripper fixed on and angularly displaceable with the shaft is engageable with the frontmost carton and carries a lever angularly coupled to the gripper and having offset from the axis two respective followers engaged in the vertical guides of the outer slide for, on vertical movement of the vertical slide, pivoting the gripper between a pick-off position engageable with the frontmost carton and a drop-off position directed downwardly above the conveyor.
Thus with this system the supply magazine does not have to be adjustable, but can be fixed relative to the frame of the unloading and erecting apparatus. When carton size is changed, it is the movement of the gripper that is varied, something that can be handled by the controller for the gripper drives. In fact normally only the vertical displacement has to be varied when carton size is changed. The frontmost carton is pulled straight out of the magazine, that is parallel to its walls, and then the carton, once it is completely free of the magazine, is then pivoted about the axis of the shaft and at the same time this axis can be moved horizontally and/or vertically so that, when the gripper is pivoted around to set the carton down on the conveyor, it is at the required height. With this system the horizontal position of the pivot axis is independent of the vertical position, making adaptation to different sizes very easy.
According to the invention the nonstraight outer vertical guides are shaped such that on vertical movement of the vertical slide the followers are alternately effective to pivot the shaft. This allows the shaft to pivot through a relatively great angle at the first stages of downward movement and the balance later. Such movement allows the structure to be very compact and the space within which the carton is moved to be kept very small also.
The magazine according to the invention is angled downward at an acute angle to the horizontal and the forward direction is horizontal. The shaft pivots through more than 90xc2x0 on movement between the take-off position and drop-off position.
In order to increase the reliability of the equipment, it further has according to the invention an inner horizontal guide on the vertical slide, an inner horizontal slide horizontally displaceable on the inner horizontal guide in the forward and backward directions relative to the vertical slide, and link means coupling the inner and outer horizontal slides together for joint horizontal movement. This link means can be a vertical guide track on the outer slide and a follower fixed horizontally relative to the inner horizontal slide and engaged therein.
The carton-unloading and -erecting apparatus further has according to the invention a stationary abutment underneath the magazine at an upstream end of the conveyor and positioned to engage a carton moved by the gripper between the take-off position and the drop-off position. In addition it has a horizontal hold-down guide extending above the conveyor downstream of an upper end thereof so that cartons on the conveyor are held down thereagainst by the hold-down guide. Each of the nonstraight vertical guides has a vertical and straight lower section and each of the nonstraight vertical guides has a vertical and straight upper section.